In motor vehicles, airbag modules are often provided at various locations to improve passive safety. These airbag modules have airbags which, in the event of an accident or collision of the vehicle, are filled with a gas via a gas generator. The vehicle occupants are cushioned by these airbags, whereby they are protected from injury on hard or sharp vehicle parts. Upon impact of a vehicle occupant with an airbag, it is important that the airbag has adequate damping properties to be able to absorb the energy of the vehicle occupant with which impact occurs and to retard "slowly" the vehicle occupant with which impact occurs.
To ensure such damping properties of an airbag, the airbags of known airbag modules are often provided with outflow openings or outflow valves. These outflow openings make it possible for the gas to escape in a specifically controlled manner from the airbag into the surroundings upon impact of the vehicle occupant, whereby the internal pressure in the airbag is reduced and the impact of the vehicle occupant with the airbag is damped. Furthermore, it is known to produce the entire airbag, or at least part of the airbag, from a gas-permeable fabric, making it possible for gas to escape through the fabric into the surroundings and consequently for the internal pressure in the airbag to be reduced during the impact of a vehicle occupant.
Recently, use has been made increasingly of airbag modules with which a long deployed time, i.e. a filled state of the airbag lasting as long as possible, is desired. These airbag modules are, in particular, socalled curtain airbag modules, which are arranged laterally in the vehicle in the region of the lateral roof members extending in the longitudinal direction of the vehicle. The airbags of such airbag modules unfold in the event of an accident in the lateral region of the vehicle essentially between the side window and the head of a vehicle occupant. Such an airbag is intended to protect the head of the vehicle occupant, in particular in the case of side impact or else rolling over of the vehicle. In particular in the case of roll over, long deployed times of the inflated airbag are required to make it possible for the vehicle occupants to be adequately protected during the entire rolling over motion of the vehicle. These deployed times are significantly longer than are known, for example, from airbag modules which are arranged in the steering wheel of the vehicle. For this reason, in the case of such airbag modules, the arrangement of the known solutions for providing adequate damping of the inflated airbag are unsatisfactory. The arrangement of outflow openings or the use of gas-permeable fabric leads to a premature escape of the gas from the airbag, as a result of which the deployed time in the inflated state of the airbag is considerably reduced. Even if larger gas generators are used, making it possible to provide a greater volume of gas and consequently replace some of the gas escaping prematurely, an adequately long deployed time of the inflated airbag cannot be achieved. Dispensing with outflow openings leads to a largely gastight airbag. In this way, although adequately long deployed times of the inflated airbag can be achieved, the impact of a vehicle occupant with the airbag is scarcely damped, with the result that the risk of injury to the occupants is greater.